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I18N::Langinfo - query locale information


use I18N::Langinfo;


The langinfo() function queries various locale information that can be used to localize output and user interfaces. It uses the current underlying locale, regardless of whether or not it was called from within the scope of use locale. The langinfo() function requires one numeric argument that identifies the locale constant to query: if no argument is supplied, $_ is used. The numeric constants appropriate to be used as arguments are exportable from I18N::Langinfo.

The following example will import the langinfo() function itself and three constants to be used as arguments to langinfo(): a constant for the abbreviated first day of the week (the numbering starts from Sunday = 1) and two more constants for the affirmative and negative answers for a yes/no question in the current locale.

use I18N::Langinfo qw(langinfo ABDAY_1 YESSTR NOSTR);

my ($abday_1, $yesstr, $nostr) =
    map { langinfo($_) } (ABDAY_1, YESSTR, NOSTR);

print "$abday_1? [$yesstr/$nostr] ";

In other words, in the "C" (or English) locale the above will probably print something like:

Sun? [yes/no]

but under a French locale

dim? [oui/non]

The usually available constants are as follows.

In addition, Linux boxes have extra items, as follows. (When called from other platform types, these return a stub value, of not much use.)


On Linux boxes, these return information about the country for the current locale. Further information is found in langinfo.h


On Linux boxes, these return meta information about the current locale, such as how to get in touch with its maintainers. Further information is found in langinfo.h


On Linux boxes, it returns 1 if the metric system of measurement prevails in the locale; or 2 if US customary units prevail.


On Linux boxes, these return information about how names are formatted and the personal salutations used in the current locale. Further information is found in locale(7) and langinfo.h


On Linux boxes, these return the standard size of sheets of paper (in millimeters) in the current locale.


On Linux boxes, these return information about how telephone numbers are formatted (both domestically and international calling) in the current locale. Further information is found in langinfo.h

For systems without nl_langinfo

This module originally was just a wrapper for the libc nl_langinfo function, and did not work on systems lacking it, such as Windows.

Starting in Perl 5.28, this module works on all platforms. When nl_langinfo is not available, it uses various methods to construct what that function, if present, would return. But there are potential glitches. These are the items that could be different:


Unimplemented, so returns "".


This should work properly for Windows platforms. On almost all other modern platforms, it will reliably return "UTF-8" if that is the code set. Otherwise, it depends on the locale's name. If that is of the form, it will assume bar is the code set; and it also knows about the two locales "C" and "POSIX". If none of those apply it returns "".


Only the values for English are returned. YESSTR and NOSTR have been removed from POSIX 2008, and are retained here for backwards compatibility. Your platform's nl_langinfo may not support them.


On systems with a strftime(3) that recognizes the POSIX-defined %O format modifier (not Windows), perl tries hard to return these. The result likely will go as high as what nl_langinfo() would return, but not necessarily; and the numbers from 0..9 will always be stripped of leading zeros.

Without %O, an empty string is always returned.


Always evaluates to %x, the locale's appropriate date representation.


Always evaluates to %X, the locale's appropriate time representation.


Always evaluates to %c, the locale's appropriate date and time representation.


The return may be incorrect for those rare locales where the currency symbol replaces the radix character. If you have examples of it needing to work differently, please file a report at


These are derived by using strftime(), and not all versions of that function know about them. "" is returned for these on such systems.

All _NL_foo items

These return the same values as they do on boxes that don't have the appropriate underlying locale categories.

See your nl_langinfo(3) for more information about the available constants. (Often this means having to look directly at the langinfo.h C header file.)


By default only the langinfo() function is exported.


Before Perl 5.28, the returned values are unreliable for the RADIXCHAR and THOUSEP locale constants.

Starting in 5.28, changing locales on threaded builds is supported on systems that offer thread-safe locale functions. These include POSIX 2008 systems and Windows starting with Visual Studio 2005, and this module will work properly in such situations. However, on threaded builds on Windows prior to Visual Studio 2015, retrieving the items CRNCYSTR and THOUSEP can result in a race with a thread that has converted to use the global locale. It is quite uncommon for a thread to have done this. It would be possible to construct a workaround for this; patches welcome: see "switch_to_global_locale" in perlapi.


perllocale, "localeconv" in POSIX, "setlocale" in POSIX, nl_langinfo(3).


Jarkko Hietaniemi, <>. Now maintained by Perl 5 porters.


Copyright 2001 by Jarkko Hietaniemi

This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.